Turbine engines are used for a number of purposes, including propulsion and/or driving various other components with electrical, pneumatic, and/or hydraulic power, and may include both propulsion engines and auxiliary power units (APUs). Generally, a gas turbine engine includes a compressor section, a combustion section, and a turbine section. During operation, the compressor section draws in ambient air, compresses the air with one or more compressors, and supplies the compressed air to the combustion section. In addition to the compressed air, the combustion section receives fuel via a fuel injection assembly, mixes the fuel with the compressed air, ignites the mixture, and supplies the high energy combustion gases to the turbine section to drive one or more turbines, including a shaft that may be used to drive the compressor and other components.
During operation, the ambient air drawn into the engine may contain undesirable particles, such as sand and dust, which may cause severe performance degradation, excessive wear, increased maintenance, and eventually premature removal of engines. In order to prevent or at least minimize these impacts, many vehicles use an inlet particle separator system, disposed upstream of the engine, to remove at least a portion of the undesirable particles. A conventional inlet particle separator typically includes a duct system having a fluid passageway that transitions into a scavenge flow path and an engine flow path. Air that is induced into the fluid passageway may have particles suspended therein. The inertia of relatively larger ones of the suspended particles tends to cause these particles to travel in a straight line rather than follow the fluid passageway. Because of the manner in which the inlet particle separator is configured, most of the suspended particles tend to flow into the scavenge flow path rather curve into the engine flow path. As such, relatively clean air is directed into the engine, and contaminated air, which has the particles suspended therein, is directed through the scavenge flow path and is discharged.
Conventional inlet particle separators, such as those described above, operate at relatively high efficiencies for relatively large particles (e.g., >20 microns, or <1000 microns). However, for relatively small particles (e.g., <20 microns, or >=1 micron), the efficiencies can be relatively low, resulting in a significant amount of these relatively small particles being ingested into the engine. These relatively small particles can still have some deleterious effects. For example, these particles can plug secondary flow lines and/or can melt and form glass on relatively hot engine components, such as the combustor, which can significantly reduce performance and the operating life of the engines.
Accordingly, there remains a need in the art for improved propulsion turbine engines and APUs. The improved propulsion turbine engines and APUs would exhibit improved particle separation efficiency, particularly with regard to fine sand particles. These engines may implement novel particle separation means that are provided in addition to or as an alternative to conventional inlet particle separators, and may be located at positions within the engine that are different as compared to conventional inlet particle separators. Furthermore, other desirable features and characteristics of the disclosure will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background of the disclosure.